Investigation of the safety features of advanced PWR assembly using SiC, Zr, FeCrAl and SS-310 as cladding materials

In this work, SiC (Silicon carbide), FeCrAl (ferritic), SS-310 (stainless steel 310) and Zirconium are simulated by MCNPX (Monte Carlo N‐Particle eXtended) code as cladding materials in advanced PWR (Pressurized Water Reactor) assembly. A number of reactor safety parameters are evaluated for the candidate cladding materials as reactivity, cycle length, radial power distribution of fuel pellet, reactivity coefficients, spectral hardening, peaking factor, thermal neutron fraction and delayed neutron fraction. The neutron economy presented by Zr and SiC models is analyzed through the burnup calculations on the unit cell and assembly levels. The study also provided the geometric conditions of all cladding materials under consideration in terms of the relation between fuel enrichment and cladding thickness from the viewpoint to achieve the same discharge burnup as the Zircaloy cladding. It was found that the SiC model participated in extending the life cycle by 2.23% compared to Zr. The materials other than SiC largely decreased discharge burnup in comparison with Zircaloy. Furthermore, the claddings with lower capture cross-sections (SiC and Zr) exhibit higher relative fission power at the pellet periphery. The simulation also showed that using SiC with a thickness of 571.15 μm and 4.83% U-235 can satisfy the EOL irradiation value as Zr. For reactivity coefficient, the higher absorbing materials (SS-310 and FeCrAl) exhibit more negative FTCs, MTCs and VRCs at the BOL But, at the intermediate stages of burnup Zr and SiC have a strong trend of negative reactivity coefficients. Finally, the delayed neutron fraction of SiC and Zr models is the highest among all the four models.

An open source tool to compute measures of inpatient glycemic control: translating from healthcare analytics research to clinical quality improvement

Objectives The objective of this study is to facilitate monitoring of the quality of inpatient glycemic control by providing an open-source tool to compute glucometrics. To allay regulatory and privacy concerns, the tool is usable locally; no data are uploaded to the internet. Materials and Methods We extended code, initially developed for healthcare analytics research, to serve the clinical need for quality monitoring of diabetes. We built an application, with a graphical interface, which can be run locally without any internet connection. Results We verified that our code produced results identical to prior work in glucometrics. We extended the prior work by including additional metrics and by providing user customizability. The software has been used at an academic healthcare institution. Conclusion We successfully translated code used for research methods into an open source, user-friendly tool which hospitals may use to expedite quality measure computation for the management of inpatients with diabetes.

THE AUNU GENERATED [ 7 4 ]-LINEAR CODE AND THE KNOWN [7 4 3 ] HAMMING CODE USING THE (U|U+V)

In this communication, we enumerate the construction of a [7 4 2]- linear code which is an extended code of the [ 6 4 1 ] code and is in one-one correspondence with the known [ 7 4 3 ] - Hamming code. Our construction is due to the Carley table for n=7of the generated points of was permutations of the (132) and (123)-avoiding patterns of the non-associative AUNU schemes. Next, [ 7 4 2 ] linear code so constructed is combined with the known Hamming [ 7 4 3 ] code using the ( u|u+v)-construction to obtain a new hybrid and more practical single [14 8 3 ] error- correcting code.

Safety Analysis of Gas Pressure in a Subcritical Assembly for Molybdenum-99 Production System

The Subcritical Assembly for Molybdenum-99 Production system is a subcritical system fueled by uranium nitrate, which utilizes the Kartini reactor’s beam port as the neutron source. One of the problems in using uranium nitrate fuel involves the radiolysis reactions and gaseous fission products that form in the cavity above the Subcritical Assembly for Molybdenum-99 Production fuel tube, resulting in a buildup of pressure. To address this issue, this study examined the total accumulated gas pressure in each Subcritical Assembly for Molybdenum-99 Production tube contributed by gaseous fission products and water radiolysis by neutron and gamma radiation during 7 days of operation. Examinations were performed by combining the Subcritical Assembly for Molybdenum-99 Production and Kartini reactor geometry to obtain the burnup power using a tally within the Monte Carlo N-Particle eXtended code. Subcritical Assembly for Molybdenum-99 Production system was then simulated for 7 days with the obtained burnup power with the same code. Outputs from the code were then calculated and analyzed to determine the total accumulated pressure on each fuel tube from each of the pressure contributors. This research showed that the maximum accumulated pressures were 0.45 atm and 0.5 atm for Kartini reactor’s power of 100 kW and 110 kW, respectively. These pressures are lower than the atmospheric pressure; hence, the current Subcritical Assembly for Molybdenum-99 Production system can be operated safely for 7 days.

Assisting in Auditing of Buffer Overflow Vulnerabilities via Machine Learning

Buffer overflow vulnerability is a kind of consequence in which programmers’ intentions are not implemented correctly. In this paper, a static analysis method based on machine learning is proposed to assist in auditing buffer overflow vulnerabilities. First, an extended code property graph is constructed from the source code to extract seven kinds of static attributes, which are used to describe buffer properties. After embedding these attributes into a vector space, five frequently used machine learning algorithms are employed to classify the functions into suspicious vulnerable functions and secure ones. The five classifiers reached an average recall of 83.5%, average true negative rate of 85.9%, a best recall of 96.6%, and a best true negative rate of 91.4%. Due to the imbalance of the training samples, the average precision of the classifiers is 68.9% and the average F1 score is 75.2%. When the classifiers were applied to a new program, our method could reduce the false positive to 1/12 compared to Flawfinder.

Core Flow Distribution from Coupled Supercritical Water Reactor Analysis

This paper introduces an extended code package PARCS/RELAP5 to analyze steady state of SCWR US reference design. An 8 × 8 quarter core model in PARCS and a reactor core model in RELAP5 are used to study the core flow distribution under various steady state conditions. The possibility of moderator flow reversal is found in some hot moderator channels. Different moderator flow orifice strategies, both uniform across the core and nonuniform based on the power distribution, are explored with the goal of preventing the reversal.

Response Functions of a Cs2LiYCl6 Scintillator to Neutron and Gamma Radiation

A new scintillator, CLYC, has been investigated for possible use in neutron spectrometry. This sensor provides neutron detection for both thermal and fast neutrons from the reactions 6Li(n,α) and 35Cl(n,p), respectively. This work primarily focuses on the detection of fast neutrons since there is currently no sensor that can accurately and efficiently provide information about their incident neutron energy. Conventional methods of fast neutron detection have been based on utilizing materials that use the elastic scattering process of neutrons on 1H to create recoil protons or by thermalizing and capturing these neutrons at thermal energies. Both approaches have drawbacks and are complex in deriving the energy spectrum through the unfolding process. The CLYC scintillator uses a distinct proton peak, whereby the position on the spectrum is proportional to the energy of the incident neutron. The response function of this detector has been simulated using Monte Carlo N-Particle eXtended code (MCNPX) for gamma-rays and neutrons of different energies. The obtained data has been discussed and analyzed.